A:提倡民主
B:提倡科学
C:提倡新道德
D:提倡新文学
― My leg is hurt. Can you help me?
― Sorry, I am a vet. I . The doctor help you.
有一抛物线型拱桥,当水面离拱顶2米时,水面宽4米,则当水面下降1米后,水面宽度为( )